Prior to radiocarbon (14C) dating all samples are being selected and pre-treated according to the type, quantity and condition of material, and then graphitized. This is one of the most important phases in the carbon dating process, which requires highest expertise to achieve reliable and accurate result. Bone samples in Vilnius Radiocarbon laboratory are being pre-treated using exceptionally best-on-the-market chemicals and consumables and strictly following internally and internationally approved methodology.

Preferred sample size: >2 g
Minimum sample size: 600 mg
The bone is composed of three primary components: mineral, organic, and water. Approximately 30% of the dry sample weight comprises organic matter, while the remaining 70% consists of non-organic material. Within the organic fraction of bone, proteins and minimal lipid content are present. Collagen, the most significant protein, constitutes 90-95% of the total organic material and it is one of the most reliable fractions for dating.

The preservation quality of bone collagen is mainly influenced by environmental factors. Collagen tends to be well-preserved in cooler climates and under moderate pH conditions. However, in highly acidic soils, the mineral part of the bone undergoes gradual dissolution, leading to the degradation of collagen.

Additionally, collagen is remarkably sensitive to chemical breakdown in highly alkaline soil environments.

The preparation of bone samples involves standard acid-base-acid (ABA) procedure and collagen extraction. Firstly, bone samples are ultrasonicated in ultrapure water, dried, grinded and sieved to get the appropriately sized sample fraction (0.5–1 mm). Then samples are treated with 0.5M hydrochloric acid (~18 hr), 0.1-0.2M sodium hydroxide (30 min-1h), and 0.5M hydrochloric acid (1 hr). Bone collagen gelatinization is performed in pH 3 solution at 70°C for 20 hr. Gelatine solution is filtered using a cleaned Ezee-filter and freeze-dried. The quality of collagen is a critical factor in radiocarbon dating. It is monitored by carbon and nitrogen content in collagen, atomic C/N ratio determination and collagen yield. Samples are dated if the collagen yield is above 1% and the C:N ratio of the collagen is between 2.9 and 3.5. The samples that deviate from these ratios are deemed unsuitable for dating.

If collagen of the sample is not suitable for dating, and you do not have an alternative suitable sample, we can perform AMS radiocarbon dating of bone from bioapatite. Bioapatite is a mineral component of bone, and carbonates within these materials can be targeted for dating. Please keep in mind that collagen reflects more reliable time range due to different uptake of carbon, but in the extraordinary cases it can still give a useful information.

Before sending the sample, we recommend to check here, how your sample’s result in the dating certificate will look.